Recently, the demand for high-density granular detergents having an apparent specific gravity of at least 0.5 g/cm.sup.3 is ever increasing, since high density detergents conserve resources. Furthermore these detergents are easy to carry, which makes them convenient for consumers.
Typical methods for the production of high-density granular detergents include those described in JP-A-61-64798,JP-A-61-66798, JP-A-61-69897, JP-A-61-69898, JP-A-61-69899, JP-A-61-69900, JP-A-61-76597 and JP-A-61-118500. (The term "JP-A" as used herein means a published unexamined Japanese patent application).
These methods enable the production of high-density granular detergents having excellent characteristics in some respects However, the methods described in JP-A-61-64798, JP-A-61-69897, JP-A-61-69898, JP-A-61-69899 and JP-A-61-69900 each include a spray drying step which is conventionally employed in the production of powdery detergents. Therefore, the above methods are disadvantageous in that a large apparatus and high energy consumption are required for the spray drying.
On the other hand, the methods described in JP-A-61-66798, JP-A-61-76597 and JP-A-61-118500 do not include a spray drying step, and are thus free from the above problem. However each of these methods include a grinding step where the material is ground to have a hardness exceeding a predetermined level. Thus, the moisture content of the starting materials is limited, such that the selection of starting materials for use in these methods is restricted.